1. Field of the Invention
This invention relates to a guiding apparatus for guiding an extended nip press blanket relative to a pressing shoe. More specifically, this invention relates to a guiding apparatus for guiding an extended nip press blanket relative to a pressing shoe of an enclosed, or so-called "apple type" extended nip press.
2. Information Disclosure Statement
In the prior art, it is known to provide a felt-supported web which extends through an extended nip defined by an elongate hydraulically-loaded shoe and a rotatable backing roll. A flexible blanket is disposed between the shoe and the felt such that as the blanket slides over the shoe and through the extended nip, the blanket is pressed towards the backing roll with the felt disposed between the blanket and the web for dewatering the formed web.
The extended nip press blanket usually includes a urethane material and is guided relative to the shoe by means of guide rolls disposed upstream and downstream respectively relative to the shoe. In order to maintain the correct alignment of the blanket relative to the shoe, one of the guide rolls includes adjustable journal bearings such that the axis of the guide roll relative to the shoe can be adjusted, or skewed, in order to guide the blanket laterally relative to the shoe.
In View of the requirement for supplying lubricant between the shoe and the blanket passing thereover, certain problems have been experienced in the prior art proposals in that this lubricant sometimes contaminates the supported felt and web. Because of this tendency towards contamination and marking of the resultant web, a totally enclosed shoe has been proposed. The afore-mentioned enclosed shoe arrangement known as the "apple extended nip press" is disclosed in U.S. Pat. No. Re. 31,923 assigned to Beloit Corporation. The "apple extended nip press" includes a blanket which is guided in an apple-shaped configuration through the extended nip and continuously around support means.
U.S. Pat. No. 4,673,461 to Roerig et al and assigned to Beloit Corporation teaches an annular flexible seal which extends between a rotatable head and the edge of the blanket for enclosing the blanket and preventing lubricant from contaminating the web.
However, with the provision of the totally enclosed blanket, the aforementioned guiding rolls for adjusting the skew of the blanket are not possible because no guiding rolls are used in the "apple extended nip press" configuration.
The present invention provides means for guiding the blanket relative to the shoe, such means enabling skewing of the blanket relative to the shoe so that lateral alignment of the blanket relative to the shoe is possible.
Therefore, it is primary objective of the present invention to provide a guiding apparatus which overcomes the problems associated with the aforementioned proposals and which provides a significant contribution to the extended nip pressing art.
Another object of the present invention is the provision of a guiding apparatus for guiding an extended nip press blanket relative to a pressing shoe in which a nose member pivotally-connected to the shoe guides the blanket relative to the shoe.
Another object of the present is the provision of a guiding apparatus which includes actuating means secured to the shoe for pivoting the nose member relative to the shoe.
Another object of the present invention is the provision of a guiding apparatus which includes connecting means extending between the actuating means and the nose member for connecting the actuating means to the nose member such that when the actuating means is actuated, the nose member is skewed relative to the shoe so that the blanket is guided laterally relative to the shoe as the blanket moves over, and in contact with, the nose member.
Another object of the present invention is the provision of a nose member which defines an elongate convex surface which contacts the blanket such that the blanket moves in a direction over the convex surface of the nose member onto the shoe.
Another object of the present invention is the provision of a guiding apparatus in which the nose member includes a central portion having a first and a second end with the first and second extension extending laterally from the first and second ends, the central portion being pivotally-connected to the shoe such that the nose member pivots midway between the first and second ends of the central portion.
Another object of the present invention is the provision of a guiding apparatus which includes a tongue portion extending from the shoe in a direction opposite to the machine direction and a first pivot pin extending from the tongue portion such that the nose member pivots midway between the first and the second end of the central portion about the first pivot pin.
Another object of the present invention is the provision of a guiding apparatus in which the nose member also includes a projection. The projection is slidably received within a slot defined by the shoe so that a second pivot pin extending into the shoe and through the slot pivotally secures the nose member relative to the shoe.
Another object of the present invention is the provision of a guiding apparatus in which the shoe includes a supporting portion which extends from the shoe for supporting the nose member such that during pivotal movement of the nose member relative to the shoe, the support portion supports the nose member with the nose member being disposed between the blanket and the support portion.
Another object of the present invention is the provision of a guiding apparatus including a first and a second arm which extend respectively from the first and second ends of the central portion to respectively the first and second sides of the shoe. The first and second arms define respectively a first and second longitudinal guideway for the reception therein of the first and second extensions respectively such that skewing of the nose member relative to the shoe is permitted.
Another object of the present invention is the provision of a guiding apparatus in which a third and fourth extension extend laterally relative to the central portion with the third and fourth extensions cooperating respectively with first and second grooves defined respectively by the first and second arms such that skewing of the central portion relative to the shoe is permitted, the skewing being only in a plane parallel to the plane of the blanket when the blanket is guided from the nose member onto the shoe.
Another object of the present invention is the provision of a guiding apparatus in which the actuator is an air cylinder pivotally-secured to the shoe.
Other objects and advantages of the present invention will be apparent to those skilled in the art by a consideration of the detailed description contained hereinafter taken in conjunction with the annexed drawings.